title: Cyclo(L-Pro-D-Arg): a new antibacterial and antitumour diketopiperazine from Bacillus cereus associated with a rhabditid entomopathogenic.
abstract: In continuation of our search for new antimicrobial secondary metabolites from Bacillus cereus associated with rhabditid entomopathogenic nematode, a new microbial diketopiperazine, cyclo(L-Pro-D-Arg), was isolated from the ethyl acetate extract of fermented modified nutrient broth. The chemical structures of the isolated compounds were identified based on their 1D, 2D NMR and high-resolution electrospray ionisation-mass spectroscopy data. Antibacterial activity of the compound was determined by minimum inhibitory concentration and disc diffusion method against medically important bacteria, and the compound was recorded to have significant antibacterial activity against test bacteria. The highest activity was recorded against Klebsiella pneumoniae (1 μg/mL). Cyclo(L-Pro-D-Arg) was recorded to have significant antitumor activity against HeLa cells (IC50 value 50 μg/mL), and this compound was recorded to have no cytotoxicity against normal monkey kidney cells (VERO) up to 100 μg/mL). To the best of our knowledge, this is the first time that cyclo(L-Pro-D-Arg) has been isolated from a microbial natural source.
authors.affiliation: Division of Crop Protection/Division of Crop Utilisation, Central Tuber Crops Research Institute, Sreekariyam, Thiruvananthapuram, 695017, India, micronishanth@rediffmail.com.
authors.forename: S Nishanth
authors.initials: SN
authors.lastname: Kumar
authors.forename: C
authors.initials: C
authors.lastname: Mohandas
authors.forename: Bala
authors.initials: B
authors.lastname: Nambisan
authors.forename: R S
authors.initials: RS
authors.lastname: Sreerag
authors.forename: C A
authors.initials: CA
authors.lastname: Jayaprakas
mesh_terms: D000818:Animals; D000900:Anti-Bacterial Agents / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology*; D000970:Antineoplastic Agents / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology*; D001409:Bacillus cereus / Q000737:chemistry / Q000378:metabolism*; D002470:Cell Survival / Q000187:drug effects; D002522:Chlorocebus aethiops; D054659:Diketopiperazines / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology*; D006367:HeLa Cells; D006801:Humans; D008826:Microbial Sensitivity Tests; D008958:Models, Molecular; D015394:Molecular Structure; D019906:Nuclear Magnetic Resonance, Biomolecular; D010456:Peptides, Cyclic / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology*; D017168:Rhabditida / Q000382:microbiology*; D014709:Vero Cells
chemical_list: D000900:Anti-Bacterial Agents; D000970:Antineoplastic Agents; D054659:Diketopiperazines; D010456:Peptides, Cyclic